Water monitoring network

ANDRA has been monitoring water quality across the whole of the OPE zone since 2007. In 2011, working in collaboration with the LNE (National Metrology and Testing Laboratory) and the AESN (Seine-Normandy Water Agency), it created a network for monitoring surface and underground water. This network tests water quality and analyses the ecological and chemical properties of the various bodies of water in this region, in line with regulatory requirements.

Surface water

Background

The largest water courses in the OPE zone are:

  • the Marne, in the West
  • the Ornain in the East, an affluent of the Marne.

Secondary water-courses include, from West to East:

  • the Saulx,
  • the Orge,
  • the Ormançon,
  • the Barboure,
  • in the South the Rongeant, an affluent of the Marne,
  • in the South-West the Ognon, which forms the Ornain at its confluence with the Maldite to the south of Gondrecourt-le-Château.

The OPE zone is also traversed by the Marne-Rhine canal.

Of all the different aspects of the environment that we study, water quality often gives the best idea of the state of the environment thanks to its role in the transport of contaminants, regardless of their nature or concentration. In addition, water monitoring is subject to strict regulations (protective measures and controls), all of which are justified given its important role in the food chain (provision of drinking water, irrigation etc.).

System

In addition to the regulatory monitoring of surface water carried out by the Meuse/Haute-Marne Centre at ANDRA, an initial network for quantitative and qualitative water monitoring was put in place between October 2007 and December 2008 within the OPE zone, collecting data from 16 surface water sites along the Saulx, Orge, Ornain, Ormançon and Maldite rivers and the Marne-Rhine canal. These studies (chemical and biological analysis) were accompanied by measurements of sediment and bryophytes.

In 2010, the ANDRA worked with the LNE to produce an expert report on temporo-spatial variations in water quality. The results were then used to create a monitoring network that could be used to track water quality within the OPE reference area. This new network, comprising 17 stations, was set up in 2011 in partnership with the AESN, the idea being to integrate the networks that were recently defined in application of the DCE (Water Framework Directive) and to implement the analysis programmes, not only in order to meet the ANDRA's monitoring requirements but also to assess changes in the ecological and chemical properties of the various bodies of water in line with DCE requirements.

The stations were chosen in such a way as to ensure water quality could be monitored both up- and down-stream of the OPE reference area. The results included:

  • an expert report on the temporo-spatial variability of physical and chemical properties and microcontaminant levels in the three sub-basins (Orge, Ornain, Saulx),
  • the various anthopogenic pressures on the study area (agriculture, businesses, urban development, future industries etc.),
  • the existence in the basin of monitoring stations operated by the AESN, such as RCS (Surveillance Control Network), RCO (Operational Control Network) and RCB (Additional Basin Network).

Surface water mapSurface water map

Salient features

These water-courses are notable for their nitrate levels which, depending on the monitoring station, are rated as good to poor. This is largely due to the agricultural nature in the study area. The stations least affected were those at the head of the Ornain's drainage basin, especially during summer months, due to the plant coverage which absorbs and limits the leaching of nitrates. Bacteriological quality at the stations varied between poor and very good. However, the "very good" rating in fact only applied to one station, that on the Marne-Rhine canal. Bacteriological quality at the stations was related to the influx of untreated or partially-treated household effluent and to the fact that livestock have access to the water. Microcontaminant quality (organic microcontaminants not including pesticides and metallic microcontaminants) was mostly good or even very good; however sometimes a few one-off metal element readings meant a 1- or 2-point drop below the threshold levels for "good ecological status" as set by the Water Framework Directive. The metal elements in question are zinc, copper and chrome. These contamination levels which are isolated in space and time are probably anthropogenic in origin. It should be noted that these metals were not detected in the bryophytes that were analysed, indicating a low bioavailability. As regards pesticides, water quality was rated "very good" at all stations. Traces of phytosanitary molecules, due to the agricultural nature of the region, were however detected, but not to the extent that they affected this "very good" rating. The results of the bryophyte metal analyses were generally "very good", with a few one-off exceptions due to the presence of nickel, mercury or copper. These contaminations were isolated in time, and there was no particular connection between the stations.

As regards the factors that caused these deteriorations, there are several possible hypotheses as to the origin:

  1. a surface cause as a result of the anthropogenic activities identified across the OPE zone: agriculture (crops and livestock) which are a source of nitrates, pesticides, metals and organic matter which encourages bacterial growth, with pollution also possibly coming from domestic waste (some towns had no waste-water processing plant); past or present industrial activity (a former railway line across the Ornain's drainage basin; the former foundry on the Saulx) which could explain the presence of certain metal microcontaminants (copper, nickel, lead etc.).
  2. An underground origin from both the water table which could bring nitrates and pesticides if it feeds water courses, and from the geochemical background which could explain the presence of certain microcontaminants (especially arsenic and zinc).

The extent of the influence on water quality is dependent on hydrological factors and climate.

Underground water

System

The underground water in the OPE zone is already extensively monitored as part of the AEP's surveillance programme (RNSISEAU - the National Monitoring Network, as part of the quality control of raw water used for drinking water production) and as part of the CMHM's water monitoring at several of ANDRA's bore-wells.

As part of the 2011 overhaul of the underground monitoring programmes for the OPE zone, 7 bore-wells were selected based on geographical location and used to track changes in water quality and to help further our understanding of transfers with surface water. Parameters and the analysis frequency were determined based on the control programmes recently established as part of the DCE. All these data will be entered into the AESN and BRGM databases.

Underground water mapUnderground water map

Salient features

Our analysis of underground water revealed contrasting situations as regards the extent of pesticide contamination. The bore-wells at the Meuse-Haute-Marne Centre and the one at Blussey saw the quality of their water change from good (water similar in composition to natural water, but detection of some anthropogenic contamination) to very bad (significantly worse in quality compared to water in its natural state). The molecule that had the biggest effect was Diuron (an active herbicide). This is a result of the fragility of the aquifer in the calcareous rock of Barrois (a karstic environment which surface water reaches quickly) in relation to the anthropogenic activities on the surface.

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